In the field of animal feed processing, wet and dried distiller grains are a major feed source for farm livestock. This is due in part to the increased commercial interest in ethanol production. Wet distiller grains are one of the residual products of grain fermentation that forms during the production of ethanol. This residue, which is sometimes called mash, has relatively high water content in the range of about 60-70% and has a high nutritional value, which is a good supplemental food source for livestock.
However, one of the major problems with wet distiller grains is that it is susceptible to mold and mildew when exposed to air for about 4 to 5 days. This potential mold and mildew issue makes it imperative that the wet grains are used and consumed relatively quickly, because extended storage of wet grains is not feasible. To address the mold and mildew issues with wet grains, oftentimes, a drying process is applied to the wet grains prior to their delivery as livestock feed. Typically, the wet grains are treated in rotating drying drums where combustion gases are heated to approximately 900 degrees Fahrenheit and then injected into the wet grains to evaporate the excess moisture. At the conclusion of the drying process, the wet grains are transformed into dried distiller grains having moisture content in the range of 10 to 15% water. The dried grains are a more desirable livestock feed in that they are not as susceptible to mold or mildew given their lower water content. Dried grains therefore have longer storage life. The dried grains have an added benefit in that they are more concentrated and therefore contain more nutritional value per unit volume than wet grains.
While dried grains have several advantages over wet grains, they do have some properties that make them less than desirable as a livestock feed. First, the dried grains have a loose and granular consistency which makes them susceptible to dilution and spoilage when spread on the ground as feed and exposed to the weather. In this loose granular form, the livestock consuming the dried grains do not receive the full potential benefit of the nutritional value of the feed, because of the relatively low density of the material. Second, transportation of loose granular material such as dried grains also presents material handling issues when compared to more dense bulk material. Another serious concern with dried grains is the safety of the drying process that transforms wet grains to dried grains. Given that the drying process generally takes place in a rotating drum with an open boundary between the grain and the heated combustion gases, there is a constant danger of potential explosions within the volatile atmosphere inside the drying drum. This problem can be a major safety hazard for personnel operating the dryers and it can cause down time and increased capital cost.
To address the low density concerns associated with the loose granular dried grains, pelletizing of dried grains has been implemented by many livestock feed manufacturers. In some conventional methods, the pellets or range cubes are formed by compressing dried grains with the addition of binder materials or supplements that help the resulting pellet become dense and cohesive. While this solution is an improvement over the loose granular dried grains, the addition of supplements to the dried grains results in an increase in cost and lowers the nutritional value per unit volume of the final product in comparison to a dried grain pellet produced without such binders and supplements. One of the main problems with the pellets and cubes produced from this conventional technique is that they are made with binders and fillers, to keep them together. Even with these additives, the pellets and cubes can fall apart. Thus, it may be desirable to produce a cube or pellet having the highest protein and fat content, as naturally possible. A system and method is needed that produces a sufficiently dense pellet having the highest fat and protein content, without adding any binders, which are non-natural additives like molasses.
Some of the conventional pellet producing methods require a heating or curing process applied to the pellet or cube after it is formed in order to boil off the corn oil, which also lowers the protein level. Thus, there is a need to provide a method that does not require a heating or curing process after the pellet or cube is produced.
After the pellet is made, it must be transported from the manufacturing facility to the farmer. Typically, during transport, the product is subjected to several intermediate transfers using an auger. The cattle feed industry currently produces cube and pellets that cannot be augured several times. Even with the increase in product density, the resulting product that includes binders and supplements does not have sufficient density and cohesiveness to maintain their structural integrity when subjected to the repeated stress of being augured several times during transport. This repeated stress can cause the product to break apart or become damaged. Thus, there is a need to produce a product that is capable of being purchased in bulk, being transported via rail car or semi-trailer load, being augured several times during transport, and, upon arrival at its destination, being augured by the existing feeding system that the cattle farmer already has installed.